Field of the Invention:
The invention relates to a cutting tool support, especially on a rotating cylinder in rotary printing presses, and more particularly to a device for cutting a web of material in a folder, particularly, of rotary printing presses, the cutting device having a cutting tool, such as a knife, accommodated on a cutting cylinder, and pressure bars of elastic material flanking the cutting tool or knife with which the pressure bars are in immediate contact, the pressure bars projecting resiliently beyond or past a jacket of the cutting cylinder.
German Patent 1 611 282 relates to a device for cutting a paper web in a folder. A cutting knife is secured between clamping bars in a knife cylinder formed with a longitudinal groove. The cutting knife is flanked on both sides thereof by resilient pressure bars of soft elastic plastic material which directly contact the cutting knife and project beyond the jacket of the knife cylinder. The pressure bars have a radially outwardly extending taper in the region of the length thereof projecting beyond the jacket of the knife cylinder, and impart a given elastic resilience in the circumferential direction to the cutting knife.
The published German Patent Document DE 44 24 919 C1 is concerned with a cutting knife bar of a cutting cylinder in folding units of web-fed rotary printing presses. To support a cutting knife in a vibration-damping manner and to avoid damage to a product or copy, contact-pressure strips or bars of synthetic rubber with a fine cellular structure are used.
The published German Patent Document DE 42 44 786 A1 is concerned with a device for adjusting a cutting knife bar or strip for a cutting cylinder in a rotary printing press. In this adjusting device, there is provided a device for displacing cutting knife strips or bars on a cutting cylinder for cutting a length of paper web crosswise both for collect-run and noncollect-run production which should be of compact construction and simple to operate. This is achieved by providing the cutting knife strips or bars, on a bottom surface thereof, with circular slits in an acute angle, with stay bolts engaging in the slits and, in turn, being movable by a drive in axial direction, so that the cutting knife strips or bars are capable of moving circumferentially on the cutting cylinder.
In high-speed folders, multilayer lengths of paper web entering between the pair of cutting cylinders exert major forces on the cutting tool support. The half of the cutting knife support oriented towards the web of material is especially severely stressed. Due to the high stress and the elasticity of the pressure bars, premature fatigue can occur thereat, which becomes apparent by the development of cracks in the material of which the pressure bars are formed. This impairs the support of the cutting tool on both sides thereof.